Atomic forces in Fermi-Löwdin local orbital self-interaction correction calculations

We present a derivation of atomic forces for density functional theory calculations with the Perdew-Zunger self-interaction-correction. The forces consist of the Hellmann-Feynman contributions and the Pulay corrections that are required when an atom-centered basis set is used. The method has been incorporated in the FLO-SIC code, which implements the Fermi-Löwdin local orbital (FLO) approach to the self-interaction correction (SIC). We present results of using this method for several small molecules and show that they agree well with corresponding results obtained using finite differences of self-consistent total energies. We also show the results of using the calculated forces to optimize molecular geometries in FLO-SIC.